Screening embryos -- for AS?

A New York Times article about preimplantation genetic diagnosis (PGD) -- essentially, screening embryos for the risk of inherited diseases -- contains something about a woman with AS that just floored me:

Dr. Ina N. Cholst, a reproductive endocrinologist at Weill Medical College of Cornell University, said a fertility patient of hers who suffers from an inherited arthritic condition called ankylosing spondylitis was planning to add genetic diagnosis to her in vitro procedure. She has a 50 percent chance of passing the gene to a child. Of those who carry it, four of five will be unaffected. The others will have arthritis, sometimes mild and sometimes quite severe, but increasingly treatable.

In other words, screening for HLA-B27. As a counterpoint, I was told at an AS seminar that my diagnosis was not grounds not to have children. The idea that our condition could be screened against -- well, I've got mixed feelings about that.